package cn.edu.njust.alg.jisuanke;

import java.util.Scanner;

public class Main_007 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s1 = sc.next();
		String s2 = sc.next();
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < s1.length(); i++) {
			char c1 = s1.charAt(i);
			char c2 = s2.charAt(i);
			sb.append(1& ~((c1 - '0') ^ (c2 - '0')));
		}
		System.out.println(sb.toString());
		sb.length();
		sc.close();
	}
}
